Retainer key for pedestal side frames

ABSTRACT

Key for retaining an axle bearing assembly between spaced vertical pedestal walls which define an open-bottomed jaw in a railway truck side frame on a railway car. The key has a one piece body consisting of a base portion, an inner retainer end portion and an upper stabilizing arm. The base portion is seated on an external flange on one of the pedestal walls and the bottom is formed to seat against upwardly and inwardly facing support surfaces on the flange to prevent downward and outward displacement of the key. The inner retainer end portion extends through an access opening in the pedestal wall above the flange and engages the underside of the axle bearing assembly to hold it in the jaw regardless of up and down oscillation of the railway car relative to the truck. The stabilizing arm extends upwardly from the base section and engages the outside of the pedestal wall above the access opening. A downward force exerted by the axle bearing assembly on the retainer end portion produces a force couple about an axis on the flange. This is resisted by an opposite, balancing reactive force couple about the same axis resulting from a thrust reaction between the stabilizing arm and the one pedestal wall. This holds the key stably in position to retain the axle bearing assembly in the jaw.

United States Patent [191 resch [111 3,831,531 [4 1 Aug. 27, 1974 RETAINER KEY FOR PEDESTAL STDE [75] Inventor: Herman D. Wresch, Wheeling, Ill. [73] Assignee: MacLean-Fogg Lock Nut C0.,

Mundelein, I11.

[22] Filed: Mar. 16, 1973 [21] Appl. No.: 341,956

[52] US. (11. 105/221 K, 295/36 A, 295/4 Z [51] lnt. Cl. B6lf 5/28, B61f 5/52, 8611'" 15/20 [58] Field of Search... 105/218 R, 220, 221, 224 R, 105/221 K; 295/36 A, 4 Z

[56] References Cited UNITED STATES PATENTS 1,530,127 3/1925 Larsen .l 105/220 1,799,943 4/1931 Alden 105/218 R X 1,875,770 9/1932 Stertzbach 105/220 2,234,413 3/1941 Orr 105/221 3,521,570 7/1970 Haster, Jr 105/224 R X Primary ExaminerLloyd L. King Assistant Examiner-Howard Beltran Attorney, Agent, or Firm-Davis, McCaleb & Lucas [57] ABSTRACT Key for retaining an axle bearing assembly between spaced vertical pedestal walls which define an openbottomed jaw in a railway truck side frame on a railway car. The key has a one piece body consisting of a base portion, an inner retainer end portion and an upper stabilizing arm. The base portion is seated on an external flange on one of the pedestal walls and the bottom is formed to seat against upwardly and inwardly facing support surfaces on the flange to prevent downward and outward displacement of the key. The inner retainer end portion extends through an access opening in the pedestal wall above the flange and engages the underside of the axle bearing assembly to hold it in the jaw regardless of up and down oscillation of the railway car relative to the truck. The stabilizing arm extends upwardly from the base section and engages the outside of the pedestal wall above the access opening. A downward force exerted by the axle bearing assembly on the retainer end portion produces a force couple about an axis on the flange. This is resisted by an opposite, balancing reactive force couple about the same axis resulting from a thrust reaction between the stabilizing arm and the one pedestal wall. This holds the key stably in position to retain the axle bearing assembly in the jaw.

6 Claims, 9 Drawing Figures PATENTED AUB 2 7 I974 BACKGROUND OF THE INVENTION The field of invention is side frame keys for American Association of Railroads standard," and alternate standard, pedestal type side frames for railway trucks.

In a standard railway car there are, of course, two, wheel-mounted trucks, one at each end of the car. Each truck includes a pair of side frames interconnected by a transverse beam-like truck bolster which extends crosswise of the car and is pivoted through a center plate to the underside of a longitudinal center beam or bolster on the body.

In old designs of built-up trucks, a casting of some what the form of an inverted letter U was bolted to each truck frame holding a corresponding axle journal box in its place horizontally, but permitting it to move vertically. These U shaped castings were called pedestals and the two spaced vertical walls were called pedestal legs. The space between the legs was called a jaw and this was closed at the bottom by a pedestal tie bar extending across the mouth of the jaw underneath the so-retained journal box.

Modern truck side frames are now generally cast in one piece, and the axles are supported on roller bearings instead of journal bearings, but much of the old nomenclature remains in use. The portion of the side frame receiving the roller bearing is still called a pedestal. It has a pair of spaced, vertical pedestal walls defining an open-bottomed jaw within which the axle bearing is mounted for limited up and down movement. For clarity, to those not necessarily conversant with the railway parlance, the term pedestal walls will be used in the following description instead of pedestal legs. At the bottom or mouth of the jaw, a side frame key is mounted on one of the pedestal walls and extends into the jaw beneath the axle bearing assembly to retain it in the jaw.

It is this side frame key with which the present invention is concerned.

Conventional side frame keys comprise a body having a base portion bolted in a flange carried by one of the pedestal walls externally of the jaw. A retaining end portion extends through an opening into the jaw beneath the axle bearing assembly and serves as a keeper, holding it in the jaw regardless of up and down oscillations of the car.

These conventional side frame keys have a serious disadvantage. They are held on the pedestal wall flange by a bolt and nut connection. Through normal train operations (oscillation of the car which lifts the axle and wheel), downward impact of the axle bearing assembly on the key stresses the bolt-nut assembly beyond the yield point, the nut loosens and backs off. The key falls out and is lost. This leaves no way of retaining the axle and wheel with the car under severe oscillating conditions. This is dangerous and can result in car derailment. The American Association of Railroads considers this so serious that it has issued a special warning alerting all concerned members and private car owners to make prompt repair or replacement of these keys until such time as a cause and solution are determined.

BRIEF SUMMARY OF THE INVENTION A general object of the present invention is to provide a railway truck side frame key having strength and positional stability which are completely independent of any bolt or other means for retaining it on a pedestal wall.

An important object of the invention is to provide a side frame key with a unique upper stabilizing arm engageablewith the pedestal wall externally of the jaw to thereby resist downward displacement of the inner retaining end portion of the key by reason of a novel thrust reaction between the stabilizing arm and the pedestal wall.

A specific object of the invention is to provide such a side frame key seated on a flange on the pedestal wall, the key having an inner retaining end portion extending into the jaw below the axle bearing assembly, and also having an upper stabilizing arm engaging the pedestal wall above the flange, whereby a downward impact from the axle bearing assembly on the inner retaining end portion, producing a force couple about an axis on the flange, will be resisted by an equivalent thrust reaction between the stabilizing arm and the pedestal wall to produce a balancing reactive force couple about the same axis for keeping the key on the flange without stressing the bolt or other key-fastening means.

A primary feature of the invention is the provision of a railway truck side frame key having an upper stabilizing arm. Another feature is utilizing such arm to stabilize the key against stresses that cause loss of conventional keys.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary side view of a railway car showing a specific application of the present invention;

FIG. 2 is a fragmentary, enlarged view of FIG. 1;

FIG. 3 is a fragmentary, sectional view of any of FIGS. 2, 4 and 5, as seen in the direction of arrows 33;

FIG. 4 is a longitudinal sectional view taken along line 44 of FIG. 3, but reduced in scale for ready comparison with FIG. 2;

FIG. 5 is a fragmentary, enlarged view of FIG. 4, showing a longitudinal cross-sectional view of the new side frame key in detail;

FIG. 6 is similar to FIG. 5, but shows a conventional side frame key from the prior art; and

FIGS; 7, 8 and 9 are different perspective views of the new side frame key.

Like parts are referred to by like reference characters throughout the figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the specific embodiment of the invention illustrated in the drawings, FIG. 1 shows one end of a railway freight car 20 supported on a four wheel truck 22. There is a side frame 24 at each end of a transverse truck bolster 26. Each side frame has fore and aft pedestals 28 and 30 providing supporting connections between the car 20 and wheels 32 and 34 mounted on axles rotatable within axle bearing assemblies 36 and 38. The foregoing is conventional so will not be described in detail.

The novel side frame key will be described in connection with one of the pedestals 28, it being understood that the structure associated with the other pedestals may be the same.

Pedestal 28 includes a pair of spaced vertical'pedestal walls 40 and 42 within which the axle bearing assembly 36 is retained and guided for limited up and down movement in a jaw 44. The axle bearing assembly 36 may be a conventional roller bearing and cartridge type journal housing, and a conventional adapter 46 may be provided between the bearing assembly 26 and a horizontal wall 48 which closes the upper end of the jaw 44. The jaw 44 is open-bottomed except for the side frame key to be described.

The side frame 24 is a one piece casting, preferably steel, and includes a pair of vertical, longitudinal side walls 52 and 54 integral with the pedestal walls 40 and 42. A horizontal flange 50, which also may be an integral part of the side frame, is associated with pedestal wall 42, and extends between the side walls 52 and 54. In effect, it may be described as an outer flange on wall 54. Referring to FIG. 5, the flange 50 has an upwardly facing support surface 56, and an edge surface 58 which faces inward, that is toward the jaw 44. An access opening 60 is provided through the pedestal wall 42 above the flange 50 externally of the jaw.

The side frame key is the crux of the present invention. It comprises a one piece body preferably forged or cast of material such as steel. While the method of manufacturing is no part of the present invention, the key may be made in one piece initially or it may be fabricated in sections which are subsequently welded or otherwise fastened together. The key comprises a unitary'body having base section 64, an inner retainer end portion 66, and an upper stabilizing arm 68.

The base section 64 includes a horizontal plate 70 having a central recess 72 flanked by a pair of parallel, horizontal, bottom bearing surfaces 74, 74 seated on the upwardly facing support surface 56 of flange 50. Any suitable means for keeping the key in place on the side frame under normal transit vibrations may be provided. In this case a bolt 76 is provided, extending through openings 78 and 80 in the base plate 70 and flange 50, respectively. Nut 82 holds the bolt and keeps the key in place.

The inner retainer end portion 66 projects from the base section, through the pedestal wall access opening 60, into the jaw 44 to engage and retain the under side of the axle bearing assembly 36.

A downwardly and outwardly facing shoulder 84 (FIG. is seated against the inwardly facing edge support surface 58. The above described structure, involving key surfaces 74, 74 seated on upper flange surface 56 and key surface 84 seated against flange inner edge surface 58, prevents downward and outward movement of the key body relative to the jaw when assembled in the retaining or keeping position shown in FIG. 5.

The upper stabilizing arm 68 has an upper surface 86 which bears against the outside surface of pedestal wall 42 when the key is assembled into its retaining position shown in FIG. 5.

The advantages of the improved side frame key, using the novel upper stabilizing arm 68 are illustrated clearly by the forces, reactions and moment arms indicated by the lines and arrows on FIG. 5 as follows. Assume the axle bearing assembly 36 moves downward (or the key 62 moves upward with the side frame 24) and strikes the key with a force F, tending to rotate the key body on an arm f about a moment center or axis P extending along the flange. The abutment of the upper arm surface 86 against the pedestal wall outer surface 88 will produce a reaction R about a reaction arm r, centered on that same moment axis P. Thus, the force couple Ff which is counterclockwise about axis P in FIG. 5, will be balanced by an identical, opposite reactive force couple Rr about that same axis. The stresses will all be taken up within the key body and none will be transmitted to the bolt 76 to tend to loosen the same as has been the disadvantage in the past.

By contrast, refer to FIG. 6 which shows a prior art side frame key 62. It will be understood that FIG. 6 represents identical construction to FIG. 5 except that the stabilizing arm 68 is missing. In this case, the downward impact of the axle bearing assembly 36 on the inner end extension of the key will produce a force couple F 'f tending to rotate the key body about the moment axis P. This is resisted by a reactive force couple Rr' which, as shown in FIG. 6, is directly resisted by tension in the bolt 76. Repeated impacts on this conventional side frame key result in stretching the bolt, loosening the nut, and eventual loss of the key 62'.

While one preferred embodiment of the improved side frame key has been shown and described, it will be apparent to those skilled in the art that other specific constructions and arrangements are possible within the scope and spirit of the invention as covered by the following claims.

I claim:

1. A side frame key, for retaining an axle bearing assembly between spaced vertical pedestal walls which define an open-bottomed jaw in a railway truck side frame, said key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis at the intersection of said shoulders, said recess being engageable with a corner on one of the pedestal walls extending along said moment axis and said body having a retainer end portion engageable with the underside of an axle bearing assembly in the jaw when said key is seated in a retaining position on said one pedestal wall;

the improvement comprising:

a stabilizing arm portion extending upwardly from said base portion abuttably engageable with said one pedestal wall to resist rotation of said body by thrust reaction about said moment axis and thereby resist downward displacement of said retainer end portion in response to downward force exerted thereon by an axle bearing assembly within the jaw.

2. A side frame key, for retaining an axle bearing assembly between spaced vertical pedestal walls which define an open-bottomed jaw in a railway truck side frame, one of the pedestal walls having a horizontal support flange, said key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis, said recess being engageable along said moment axis with an upper inner comer of said horizontal support flange to prevent downward and outward movement of the body when said key is seated in a retaining position of the flange,

and said body having a retainer end portion engageable with the underside of an axle bearing assembly in the jaw when said key is seated in a retaining position on the flange;

the improvement comprising:

a stabilizing arm portion extending inwardly from said base portion abuttably engageable with said one pedestal wall outside of the jaw above the flange to resist rotation of said body by thrust reaction between said stabilizing arm portion and said one pedestal wall about said moment axis and thereby resist downward displacement of said retainer end portion in response to downward force exerted thereon by an axle bearing assembly within said jaw.

3. A side frame key, for retaining an axle bearing assembly between spaced vertical pedestal walls which define an open-bottomed jaw in a railway truck side frame, one of the pedestal walls having an opening providing access between the interior and exterior of the jaw, said one pedestal wall having a horizontal flange externally of the jaw along the lower edge of the opening, the flange having upwardly and inwardly facing support surfaces, said key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis, said recess being engageable along said moment axis with an upper inner corner of said horizontal support flange at the intersection of said upwardly and inwardly facing support surfaces to prevent downward and outward movement of the body when seated in a retaining position on the flange, said body having a retainer end portion extending from said base portion inwardly through the opening to engage the underside of an axle bearing assembly and retain it in the jaw when seated in said retaining position on the flange;

the improvement comprising:

a stabilizing arm extending upwardly from said base portion abuttably engageable with said one pedestal wall at a position outside the jaw above the opening when seated in said retaining position, whereby said body is stabilized in said retaining position by a reactive force couple produced about said moment axis by a downward force exerted on said retainer end portion by an axle bearing assembly within said jaw and a thrust reaction between said one pedestal wall and stabilizing arm outside the jaw.

4. In a railway truck side frame, a pair of spaced vertical pedestal walls which define an open-bottomed jaw, an axle bearing assembly guided for up and down movement in said jaw, a side frame key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis at the intersection of said shoulders, said recess being engageable with a corner on one of said pedestal walls extending along said moment axis and said body having a retainer end portion extending into said jaw engageable with the underside of said axle bearing assembly when the latter moves downward to a lower limit determined by said key;

the improvement comprising:

a stabilizing arm portion extending upwardly from said base portion abuttably engaged with said one pedestal wall to resist rotation of said body by thrust reaction about said moment axis and thereby resist downward displacement of said retainer end portion in response to downward force exerted thereon by said axle bearing assembly within said aw.

5. In a railway truck side frame, a pair of spaced vertical pedestal walls which define an open-bottomed jaw, an axle bearing assembly guided for up and down movement in the jaw, one of said pedestal walls having a horizontal support flange, a side frame key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis, said recess being engaged along said moment axis with an upper inner corner portion of said horizontal support flange to prevent downward and outward movement of said key body relative to said jaw, said key body having a retainer end portion extending into said jaw and engageable with the underside of said axle bearing assembly when the latter moves downward to a lower limit determined by said key;

the improvement comprising:

a stabilizing arm portion extending upwardly from said base portion abuttably engaged with said one pedestal wall outside of said jaw at a position above said flange to resist rotation of said body by thrust reaction between said stabilizing arm portion and said one pedestal wall about said moment axis and thereby resist downward displacement of said retainer end portion in response to a downward force exerted by said axle bearing assembly on said retainer end portion.

6. In a railway truck side frame, a pair of spaced vertical pedestal walls which define an open-bottomed jaw, an axle bearing assembly guided for up and down movement in said jaw, one of said pedestal walls having an opening providing access between the interior and exterior of said jaw, said one pedestal wall having a horizontal flange externally of said jaw along the lower edge of said opening, said flange having separate upwardly and inwardly facing support surfaces, a side frame key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis, said recess being engaged along said moment axis with an upper inner corner of said horizontal support flange at the intersection of said upwardly and inwardly facing support. surfaces to prevent downward and outward movement of said key body relative to said jaw, said key body having a retainer end portion extending from said base portion inwardly through said opening to engage the underside of said axle bearing assembly and thereby limit downward movement thereofj the improvement comprising:

a stabilizing arm extending upwardly from said base portion abuttably engaged with said one pedestal wall at a position outside said jaw above said opening, whereby a body is stabilized in said retaining position by a relative force couple produced about said moment axis by a downward force exerted on said retainer end portion by said axle bearing assembly in said jaw and a thrust reaction between said one pedestal wall and stabilizing arm outside the jaw.

"mg? UNITED STATES PATENT OFFICE CERTIFICATE CORRECTION Patoent No. 3 331 511 Dated Anglia; 21 1 225 Inventofls) erman D. Wresch It is certified that error appears in the aboue-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Clairns:

Column 6, line 59: "a" should be said and r "said" should be -a Signed and sealed this 21st day of January 1975.

' (SEAL) Attest:

McCOY M. GIBSON JR. (3. MARSHALL DANN Attesting Officer Commissioner of Patents 12;;3? UNITED STATES PATENT OFFICE CERTIFICATE QF CORRECTION Patent No. 3,831,531 Dated August 27. 1974 Ihventor(s) Herman I SCh It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Specification: I

Column 3,'linell$ "26" shouldbe 36 In theClaims;

Column 5, line D "inwardly" should be upwardly '7 Column 6, line 8;: "the" shouldbe' said Column 6, line 59: "a" should be said Column 6, line 60: "relative" should be reactive Signed and sealed this 19th dy of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A side frame key, for retaining an axle bearing assembly between spaced vertical pedestal walls which define an openbottomed jaw in a railway truck side frame, said key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis at the intersection of said shoulders, said recess being engageable with a corner on one of the pedestal walls extending along said moment axis and said body having a retainer end portion engageable with the underside of an axle bearing assembly in the jaw when said key is seated in a retaining position on said one pedestal wall; the improvement comprising: a stabilizing arm portion extending upwardly from said base portion abuttably engageable with said one pedestal wall to resist rotation of said body by thrust reaction about said moment axis and thereby resist downward displacement of said retainer end portion in response to downward force exerted thereon by an axle bearing assembly within the jaw.
 2. A side frame key, for retaining an axle bearing assembly between spaced vertical pedestal walls which define an open-bottomed jaw in a railway truck side frame, one of the pedestal walls having a horizontal support flange, said key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis, said recess being engageable along said moment axis with an upper inner corner of said horizontal support flange to prevent downward and outward movement of the body when said key is seated in a retaining position of the flange, and said body having a retainer end portion engageable with the underside of an axle bearing assembly in the jaw when said key is seated in a retaining position on the flange; the improvement comprising: a stabilizing arm portion extending inwardly from said base portion abuttably engageable with said one pedestal wall outside of the jaw above the flange to resist rotation of said body by thrust reaction between said stabilizing arm portion and said one pedestal wall about said moment axis and thereby resist downward displacement of said retainer end portion in response to downward force exerted thereon by an axle bearing assembly within said jaw.
 3. A side frame key, for retaining an axle bearing assembly between spaced vertical pedestal walls which define an open-bottomed jaw in a railway truck side frame, one of the pedestal walls having an opening providing access between the interior and exterior of the jaw, said one pedestal wall having a horizontal flange externally of the jaw along the lower edge of the opening, the flange having upwardly and inwardly facing support surfaces, said key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis, said recess being engageable along said moment axis with an upper inner corner of said horizontal support flange at the intersection of said upwardly and inwardly facing support surfaces to prevent downward and outward movement of the body when seated in a retaining position on the flange, said body having a retainer end portion extending from said base portion inwardly through the opening to engage the underside of an axle bearing assembly and retain it in the jaw when seated in said retaining position on the flange; the improvement comprising: a stabilizing arm extending upwardly from said base portion abuttably engageable with said one pedestal wall at a position outside the jaw above the opening when seated in said retaining position, whereby said body is stabilized in said retaining position by a reactive force couple produced about said moment axis by a downward force exerted on said retainer end portion by an axle bearing assembly within said jaw and a thrust reaction between said one pedestal wall and stabilizing arm outside the jaw.
 4. In a railway truck side frame, a pair of spaced vertical pedestal walls which define an open-bottomed jaw, an axle bearing assembly guided for up and down movement in said jaw, a side frame key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis at the intersection of said shoulders, said recess being engageable with a corner on one of said pedestal walls extending along said moment axis and said body having a retainer end portion extending into said jaw engageable with the underside of said axle bearing assembly when the latter moves downward to a lower limit determined by said key; the improvement comprising: a stabilizing arm portion extending upwardly from said base portion abuttably engaged with said one pedestal wall to resist rotation of said body by thrust reaction about said moment axis and thereby resist downward displacement of said retainer end portion in response to downward force exerted thereon by said axle bearing assembly within said jaw.
 5. In a railway truck side frame, a pair of spaced vertical pedestal walls which define an open-bottomed jaw, an axle bearing assembly guided for up and down movement in the jaw, one of said pedestal walls having a horizontal support flange, a side frame key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis, said recess being engaged along said moment axis with an upper inner corner portion of said horizontal support flange to prevent downward and outward movement of said key body relative to said jaw, said key body having a retainer end portion extending into said jaw and engageable with the underside of said axle bearing assembly when the latter moves downward to a lower limit determined by said key; the improvement comprising: a stabilizing arm portion extending upwardly from said base portion abuttably engaged with said one pedestal wall outside of said jaw at a position above said flange to resist rotation of said body by thrust reaction between said stabilizing arm portion and said one pedestal wall about said moment axis and thereby resist downward displacement of said retainer end portion in response to a downward force exerted by said axle bearing assembly on said retainer end portion.
 6. In a railway truck side frame, a pair of spaced vertical pedestal walls which define an open-bottomed jaw, an axle bearing assembly guided for up and down movement in said jaw, one of said pedestal walls having an opening providing access between the interior and exterior of said jaw, said one pedestal wall having a horizontal flange externally of said jaw along the lower edge of said opening, said flaNge having separate upwardly and inwardly facing support surfaces, a side frame key having a body with a base portion having a bottom surface including downwardly and outwardly facing shoulders defining an elongated recess extending along a moment axis, said recess being engaged along said moment axis with an upper inner corner of said horizontal support flange at the intersection of said upwardly and inwardly facing support surfaces to prevent downward and outward movement of said key body relative to said jaw, said key body having a retainer end portion extending from said base portion inwardly through said opening to engage the underside of said axle bearing assembly and thereby limit downward movement thereof; the improvement comprising: a stabilizing arm extending upwardly from said base portion abuttably engaged with said one pedestal wall at a position outside said jaw above said opening, whereby a body is stabilized in said retaining position by a relative force couple produced about said moment axis by a downward force exerted on said retainer end portion by said axle bearing assembly in said jaw and a thrust reaction between said one pedestal wall and stabilizing arm outside the jaw. 